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DOI: 10.1055/s-0040-1714938
Comparison of Drilling, Screw Insertion and Pullout Variables of Biaxial and Uniaxial Thread Self-Tapping 3.5 mm Cortical Bone Screws in Cadaveric Equine Third Metacarpal Bone
Publication History
Publication Date:
20 July 2020 (online)
Introduction: The effect of screw thread geometry on the holding power of screws in equine bone has not been investigated and has potential to improve outcomes in fracture repair. Our goal was to compare the drilling, screw insertion and pullout variables between a recently developed biaxial thread bone screw (BTS) and a uniaxial thread screw (UTS) in the equine third metacarpal bone (MC3).
Materials and Methods: Paired MC3 distal condyles were harvested from 8 Thoroughbreds aged 2 to 4 years. Screws (BTS or UTS) were inserted into the lateral condylar fossa following bone preparation using the respective drill bit for each screw type. Screw pullout was achieved using a mechanical testing system. Biomechanical data were compared between the two implant systems.
Results: Axial force and maximum torque were significantly lower for BTS drill bits (p = 0.008 and p = 0.028, respectively). The median of all torque peaks was 50% higher during insertion of BTS screws (p = 0.001). The UTS construct was initially 30% stiffer than the BTS construct (p = 0.002).
Discussion/Conclusion: The BTS drill bit demonstrated improved drilling properties. The greater BTS insertion torque may reflect greater bone engagement. Screw pullout properties were not different other than initial construct stiffness.
Acknowledgment: Funded by a VOS Wade O. Brinker Resident Research Award. BTS drill bit provided by OsteoCentric.